Glyphosate-resistant weeds marching north

Glyphosate-resistant and in-vasive weeds are spreading east, south and west of the central Prairies, leaving weed control officers anxiously awaiting their appearance.

No one is fooling themselves into believing these new menaces won’t appear in the cold heart of the continent.

“There’s a good chance some of them may be moving north,” said Manitoba Agriculture weed specialist Nasir Shaikh in an interview during the Canadian Weed Science Society’s annual meeting in Winnipeg Nov. 15.

Reports of glyphosate-resistant weeds appeared in many sessions during the three-day meeting, which brought together weed scientists from across the country, as well as each province’s leading weed control officers and Canadian Food Inspection Agency officials.

A host of glyphosate-resistant weeds have appeared in Ontario in recent years, and the problem is worsening.

Saskatchewan and Manitoba don’t have major problems yet, but widespread use of glyphosate creates the ideal situation for independent development of glyphosate-resistant weeds.

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As well, already-developed resistant weeds could spread into the Prairies from the much-beset U.S. Midwest and West by air, water or truck.

Herbicide resistant weeds are appearing across North Dakota, and those areas are often connected to Canadian provinces by rivers.

Last year, Manitoba Agriculture staff in Melita found a suspicious looking weed, which Shaikh was able to identify as giant ragweed, a worrisome invasive weed and a likely candidate to become glyphosate-resistant.

Giant ragweed is believed to have travelled into the Melita area in floodwaters in the past two years, and it’s not known how many other weeds from the northern United States have floated in and spread along river valleys and onto the edges of farm fields.

The war with weeds is unending. Old chemical technologies break down once weeds adapt to them and many develop multiple resistances over time. Weeds become terrible problems when glyphosate-resistance is added to their armour.

The dominance of minimum-till farming makes these problems hard to deal with and encourages even more chemical reliance.

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Alberta’s growing glyphosate-resistant kochia problem is made worse by the weed’s already existing resistance to Group 2 herbicides. It has caused major problems in Kansas.

Farmers and weed control officials have also had to grapple with the ever-present danger of invasive species. Some are agricultural and spread on farm and resource trucks and trains.

Others are introduced in urban gardens as pretty plants and then spread into farming areas.

Saskatchewan weed specialist Clark Brenzil said he has seen a worrisome ornamental weed, Himalayan Balsam, literally “jump the fence” in a Saskatoon neighbour-hood and begin spreading in a back alley.

Ontario Agriculture weed control specialist Kristen Callow described her alarm at the discovery of a patch of kudzu on a slope beside water in her province. It’s a big patch and hasn’t yet been eradicated as experts figure out how to kill it.